From e4ad45aca796d4b7a74dc7faf9f86cc9ac196d07 Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <cristianoc@users.noreply.github.com>
Date: Tue, 8 Feb 2022 12:07:58 +0100
Subject: [PATCH] When hovering on a field access, show the instantiated type
 of the field.

Related: https://github.com/rescript-lang/rescript-vscode/issues/349
---
 CHANGELOG.md                              | 1 +
 analysis/src/Hover.ml                     | 4 ++--
 analysis/src/ProcessCmt.ml                | 9 ++++-----
 analysis/src/References.ml                | 5 +----
 analysis/tests/src/Hover.res              | 5 +++++
 analysis/tests/src/expected/Hover.res.txt | 3 +++
 6 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 66ef25bb5..516db9122 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ## master
 - Fix issue where using paths of the form `./something` would show multiple copies of the same file in vscode.
+- When hovering on a field access, show the instantiated type of the field.
 
 ## 1.2.1
 
diff --git a/analysis/src/Hover.ml b/analysis/src/Hover.ml
index 32bdfe5a0..fc34f25cd 100644
--- a/analysis/src/Hover.ml
+++ b/analysis/src/Hover.ml
@@ -140,8 +140,8 @@ let newHover ~full:{SharedTypes.file; package} locItem =
               |> String.concat ", " |> Printf.sprintf "(%s)"
           in
           typeString :: codeBlock (txt ^ argsString) :: docstring
-        | `Field {typ} ->
-          let typeString, docstring = typ |> fromType ~docstring in
+        | `Field ->
+          let typeString, docstring = t |> fromType ~docstring in
           typeString :: docstring)
     in
     Some (String.concat "\n\n" parts)
diff --git a/analysis/src/ProcessCmt.ml b/analysis/src/ProcessCmt.ml
index 2a21079c2..89bf33747 100644
--- a/analysis/src/ProcessCmt.ml
+++ b/analysis/src/ProcessCmt.ml
@@ -765,11 +765,10 @@ struct
     | Ldot (_left, name) -> name
     | Lapply (_, _) -> assert false
 
-  let addForField recordType item {Asttypes.txt; loc} =
+  let addForField recordType fieldType {Asttypes.txt; loc} =
     match (Shared.dig recordType).desc with
     | Tconstr (path, _args, _memo) ->
       let t = getTypeAtPath ~env path in
-      let {Types.lbl_res} = item in
       let name = handleConstructor txt in
       let nameLoc = Utils.endOfLocation loc (String.length name) in
       let locType =
@@ -785,7 +784,7 @@ struct
           GlobalReference (moduleName, path, Field name)
         | _ -> NotFound
       in
-      addLocItem extra nameLoc (Typed (name, lbl_res, locType))
+      addLocItem extra nameLoc (Typed (name, fieldType, locType))
     | _ -> ()
 
   let addForRecord recordType items =
@@ -1004,8 +1003,8 @@ struct
       ()
     | Texp_construct (lident, constructor, _args) ->
       addForConstructor expression.exp_type lident constructor
-    | Texp_field (inner, lident, label_description) ->
-      addForField inner.exp_type label_description lident
+    | Texp_field (inner, lident, _label_description) ->
+      addForField inner.exp_type expression.exp_type lident
     | Texp_let (_, _, _) ->
       (* TODO this scope tracking won't work for recursive *)
       addScopeExtent expression.exp_loc
diff --git a/analysis/src/References.ml b/analysis/src/References.ml
index 67de8821c..f5f137d1d 100644
--- a/analysis/src/References.ml
+++ b/analysis/src/References.ml
@@ -129,10 +129,7 @@ let definedForLoc ~file ~package locKind =
       match getConstructor file stamp name with
       | None -> None
       | Some constructor -> Some ([], `Constructor constructor))
-    | Field name -> (
-      match getField file stamp name with
-      | None -> None
-      | Some field -> Some ([], `Field field))
+    | Field _name -> Some([], `Field)
     | _ -> (
       maybeLog
         ("Trying for declared " ^ tipToString tip ^ " " ^ string_of_int stamp
diff --git a/analysis/tests/src/Hover.res b/analysis/tests/src/Hover.res
index 92e6d04e5..ebe1daf30 100644
--- a/analysis/tests/src/Hover.res
+++ b/analysis/tests/src/Hover.res
@@ -87,3 +87,8 @@ let _ = <Comp> <div /> <div /> </Comp>
 
 let _ = <Comp1> <div /> <div /> </Comp1>
 //        ^hov
+
+type r<'a> = {i: 'a, f: float}
+
+let _get = r => r.f +. r.i
+//                       ^hov
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index eb3c16e32..76d322c1a 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -52,3 +52,6 @@ Hover tests/src/Hover.res 84:10
 Hover tests/src/Hover.res 87:10
 {"contents": "```rescript\n{\"children\": React.element} => React.element\n```"}
 
+Hover tests/src/Hover.res 92:25
+{"contents": "```rescript\nfloat\n```"}
+